<script setup>
 import {watch,ref} from 'vue'
 const cityname=ref("zhejiang")
 watch(cityname,(newval,oldval) =>{

    console.log(newval,oldval)
 })
 const classna='color:red'
</script>
<template>
    <input type="text" v-model.lazy="cityname" ></input>
    <div v-model></div>
</template>